DEEP: Timber Rattlesnake Fact Sheet

Crotalus horridus

State Endangered Species
{Timber rattlesnake}

Background and Conservation Concerns: The timber rattlesnake is one of only two venomous species found in Connecticut; the other is the northern copperhead. This beautifully patterned snake is extremely rare in the state and is listed as an endangered species. It was probably widespread in Connecticut during colonial times, as evidenced by the many land features named "rattlesnake" (i.e., Rattlesnake Mountain). In the past, some Connecticut towns had bounties that encouraged people to collect and kill rattlesnakes, and many dens were repeatedly decimated. Once documented in over 20 towns in Connecticut, this snake is now limited to isolated populations in about 10 towns in the central and western portions of the state. Timber rattlesnake populations have declined, mainly because of human activity and persecution, which includes illegal pet trade, intentional killing, habitat degradation and fragmentation, and human development. Protection of this snake's specialized habitats, both winter den and summer foraging/breeding grounds, is a priority.
Range: The timber rattlesnake historically occurred in 31 states, but is now found in only 27 states. It ranges from southern New Hampshire, west through the Champlain Valley, south through the Appalachian and Blue Ridge Mountains, into northeastern Texas and north along the Mississippi River to Wisconsin. A majority of the states where this species occurs (although not all) offers some protection for populations.
Description: Rattlesnakes can usually be identified by the distinctive, segmented rattle at the tip of the tail. Other distinguishing characteristics include vertical eye pupils; large heat-sensing pits between the eyes and nostrils (known as pit organs); a flattened, unmarked, triangular head about twice the size of the neck; and keeled scales (raised ridge in the center of each scale, making the skin appear rough).
This heavy-bodied snake can grow to lengths between 36 and 54 inches (average 40 inches). Both sexes are similar, although males have longer tails (not rattles). Timber rattlesnakes that occur in Connecticut usually have black or brown crossbands on a yellow, brown, or gray background. The crossbands, which may be V-shaped, break up toward the head to form a row of dark spots down the back and on each side. Sometimes the snakes are darker, with a heavy speckling of black or very dark brown that hides much of the lighter pigment.
Habitat and Diet: In Connecticut, timber rattlesnakes inhabit deciduous forests (often second growth) in rugged terrain with steep ledges, rock slides, and a nearby water supply. Dens are usually located in rocky ledges. This snake is an upland species seldom found in elevations less than 500 feet above sea level.
The timber rattlesnake feeds primarily on mice, other small mammals (voles, shrews, chipmunks, squirrels), and occasionally birds.
Life History: Connecticut’s rattlesnakes are active mid-April through October. During the colder seasons, they retreat to communal dens that may include other snake species. After emerging from dens in spring, rattlesnakes will venture in search of food, basking sites, and shelter. Males are active at this time, searching for females that have released pheromones (chemical attractants). Mating occurs in spring or fall; the females give birth to an average of 9 young in August to late September (range 5-22 young). This snake is ovoviviparous. Eggs are retained and hatched internally, resulting in live birth. Young emerge singly from the female, encased in a transparent membrane, which is shed in a few minutes. The 8- to 10-inch long young are born with a single, tiny rattle segment (button), venom, and fangs. They receive no maternal care, but are ready to fend for themselves. Males are sexually mature at about 5 years of age, while females mature at 7 to 10 years of age. Females breed every third or fourth year. The average lifespan of rattlesnakes is 16-22 years; therefore, a female may only reproduce as few as 3 to 5 times in her lifetime. Rattlesnake populations take a long time to stabilize after losing a significant number of breeding individuals due to their low reproductive rate.
Interesting Facts: Rattlesnakes (also known as pit vipers) are ambush predators that patiently wait for prey to come within reach. They use a keen sense of smell and sensory pit organs to find prey. The pit organs are located in a cavity on each side of the head between the nostril and the eye. They enable the snakes to seek out and strike accurately at objects warmer than their surroundings; this adaptation helps the snakes prey on nocturnal mammals.
Pit vipers also have large, hollow fangs at the front of their mouth that are connected to the bones of the upper jaw and palate. These fangs are folded against the roof of the mouth when the mouth is closed and are automatically brought forward when the mouth is opened. The fangs inject venom into prey. The venom is hemolytic, meaning it causes the breakdown of red blood cells in the bitten animal and this eventually subdues the animal, allowing the snake to easily swallow it. The primary purpose of venom is for eating and digestion. Therefore, a defensive strike has less and sometimes no venom compared to a prey strike.
From birth, rattlesnakes have a small rattle at the end of their tail. This rattle is keratinous (like our fingernails) and a small segment is added each time the snake sheds its skin. When these “segments” are vibrated together, a rattle-like sound is created.
Snakes and People
If you encounter a timber rattlesnake, observe it from a distance, calmly and slowly back away from it, and allow the snake to go on its way. Quick movements often scare snakes and may provoke a defensive strike. You should not try to agitate the snake by getting too close or handling it. Rattlesnakes will usually let you know if you are getting too close. All snakes will retreat from humans if given a chance.

Do NOT attempt to kill any rattlesnakes under any circumstances as this is an illegal action. Timber rattlesnakes are protected by Connecticut's Endangered Species Act and persons who kill or collect this endangered snake could be faced with fines or legal action. If you see or know of any suspicious or neglectful activity directed towards timber rattlesnakes, you can report violators to the DEEP at the 24-hour, toll-free TIP hotline (800-842-HELP) or DEEP Dispatch at 860-424-3333.

Take the time to learn about, understand, and respect this vitally important reptile, and share your knowledge with others. Also learn to identify Connecticut snakes and how to differentiate between similar-looking species. Identification help can be found by visiting the Snakes in Connecticut webpage or calling the DEEP Wildlife Division at 860-424-3011.

Amphibians and Reptiles of Connecticut and Adjacent Regions, by Michael W. Klemens (1993), was used as reference for this fact sheet.

Content last updated on March 8, 2018.